RESOLVED - Coordinate Issue - TXB2 Beaumont TX

Reported Issue:

A customer reported an elevation discrepancy on TXB2 between existing NGS benchmarks and the coordinates derived from the use of TXB2. This discrepancy was outside the normal tolerances we would expect.

Issue Resolution:

Upon investigation, it was discovered that a vertical discrepancy of ~ 6 cm existed on the published vs derived coordinates on the control check shots. In looking at the history of the site is was determined that there was an antenna change that was not properly accounted for in the previous coordinate adjustment, causing a phase offset issue.

We have recomputed the position of the station using a 14 day data set to be able to account for the ~ 6 cm height offset. This recomputed position will be an interim position until a new position is calculated as part of our bi-annual adjustment that will be completed in the next 60-90 days. Once the larger adjustment has been completed, we will publish a new "permanent" coordinate set for the station, overall change in coordinates should be in millimeter range.

You can find updates to this stations in the SmartNet Site Database - LINK

Timeline:

January 8, 2015 - Initial report of discrepancy with local control was made

January 8, 2015 - Investigation of issue was opened

January 15, 2015 - New position for TXB2 was calculated using 2 weeks of data and precise ephemeris information from data collected in early 2014, as well as 2 weeks of data collected in late 2014. These coordinate sets agreed in the millimeter range

January 15, 2015 - Comparison of new and old coordinates, review of site history, etc completed